Tip: We can only ask the Java thread to execute a piece of code, but we cannot guarantee the execution order of multiple threads!

Oracle Databases are used for traditional enterprise applications and departmental systems in large enterprises. Debezium connector for Oracle is a great way to capture data changes from the transactional system of record and make them available for application use.

The second part of how to model, structure, and organize your Infrastructure-as-Code AWS CDK Project. Building from scratch until a CI/CD pipeline composition, all the cloud component resources, and services at AWS Cloud.

A sample of how to model, structure, and organize your Infrastructure-as-Code AWS CDK Project. Building from scratch until a CI/CD pipeline composition, all the cloud component resources, and services at AWS Cloud.

Nowadays Quarkus is known as Supersonic Subatomic Java. It provides a lot of features to facilitate build and deployment.

I wrote about cypher’s MERGE function a couple of weeks ago, and over the last few days, I’ve been exploring how it works with schema indexes and unique constraints. An Exciting Time to Be a Developer There is so much that could be said about the merging of Neo4j and Cypher right now, but it is certainly reasonable to point out that this merger will likely result in many exciting developments in the programming world. Programmers virtually always appreciate it when they are given the products and tools they require to get their job done properly, and now is the time for steps like this to be taken. The fact that Neo4J and Cypher have decided to merge means that the upsides of both will soon be apparent. You deserve to use all of the best tools to make informed decisions about your next software project, and a great way to make it happen is to use what has been given to you regarding product functionality. This is to say that you can use both the upsides of Neo4J and Cypher to come up with the exact tools you need to make a difference in your sphere of influence. Could Other Products Soon Merge? There has been some strong demand for other software development products to consider merging. Coders and programmers want to use their favorite projects in exactly how they were meant to be used, and this means getting them to merge in ways that are useful to the programmers. They just want to be able to squeeze as much use out of each program as they possibly can. You want to make sure that you can see what is going on with your codes as you are directly applying them to whichever problem you are working on at this time. To be sure, it is not an easy task, but no one ever said it would be easy. The important thing is that you get the work done so that you can start to become more productive in the coding you are doing now. A common use case with Neo4j is to model users and events where an event could be a tweet, Facebook post, or Pinterest pin. The model might look like this: We’d like to ensure that we don’t get duplicate users or events, and MERGE provides the semantics to do this: MERGE (u:User {id: {userId}) MERGE (e:Event {id: {eventId}) MERGE (u)-[:CREATED_EVENT]->(m) RETURN u, e We’d like to ensure that we don’t get duplicate users or events and MERGE provides the semantics to do this: MERGE ensures that a pattern exists in the graph. Either the pattern already exists, or it needs to be created. import org.neo4j.cypher.javacompat.ExecutionEngine; import org.neo4j.cypher.javacompat.ExecutionResult; import org.neo4j.graphdb.GraphDatabaseService; import org.neo4j.graphdb.factory.GraphDatabaseFactory; import org.neo4j.helpers.collection.MapUtil; import org.neo4j.kernel.impl.util.FileUtils; ... public class MergeTime { public static void main(String[] args) throws Exception { String pathToDb = "/tmp/foo"; FileUtils.deleteRecursively(new File(pathToDb)); GraphDatabaseService db = new GraphDatabaseFactory().newEmbeddedDatabase( pathToDb ); final ExecutionEngine engine = new ExecutionEngine( db ); ExecutorService executor = Executors.newFixedThreadPool( 50 ); final Random random = new Random(); final int numberOfUsers = 10; final int numberOfEvents = 50; int iterations = 100; final List userIds = generateIds( numberOfUsers ); final List eventIds = generateIds( numberOfEvents ); List merges = new ArrayList<>( ); for ( int i = 0; i < iterations; i++ ) { Integer userId = userIds.get(random.nextInt(numberOfUsers)); Integer eventId = eventIds.get(random.nextInt(numberOfEvents)); merges.add(executor.submit(mergeAway( engine, userId, eventId) )); } for ( Future merge : merges ) { merge.get(); } executor.shutdown(); ExecutionResult userResult = engine.execute("MATCH (u:User) RETURN u.id as userId, COUNT(u) AS count ORDER BY userId"); System.out.println(userResult.dumpToString()); } private static Runnable mergeAway(final ExecutionEngine engine, final Integer userId, final Integer eventId) { return new Runnable() { @Override public void run() { try { ExecutionResult result = engine.execute( "MERGE (u:User {id: {userId})\n" + "MERGE (e:Event {id: {eventId})\n" + "MERGE (u)-[:CREATED_EVENT]->(m)\n" + "RETURN u, e", MapUtil.map( "userId", userId, "eventId", eventId) ); // throw away for ( Map row : result ) { } } catch ( Exception e ) { e.printStackTrace(); } } }; } private static List generateIds( int amount ) { List ids = new ArrayList<>(); for ( int i = 1; i <= amount; i++ ) { ids.add( i ); } return ids; } } We create a maximum of 10 users and 50 events and then do 100 iterations of random (user, event) pairs with 50 concurrent threads. Afterward, we execute a query that checks how many users of each id have been created and get the following output: +----------------+ | userId | count | +----------------+ | 1 | 6 | | 2 | 3 | | 3 | 4 | | 4 | 8 | | 5 | 9 | | 6 | 7 | | 7 | 5 | | 8 | 3 | | 9 | 3 | | 10 | 2 | +----------------+ 10 rows Next, I added a schema index on users and events to see if that would make any difference, something Javad Karabi recently asked on the user group. CREATE INDEX ON :User(id) CREATE INDEX ON :Event(id) We wouldn’t expect this to make a difference as schema indexes don’t ensure uniqueness, but I ran it anyway t and got the following output: +----------------+ | userId | count | +----------------+ | 1 | 2 | | 2 | 9 | | 3 | 7 | | 4 | 2 | | 5 | 3 | | 6 | 7 | | 7 | 7 | | 8 | 6 | | 9 | 5 | | 10 | 3 | +----------------+ 10 rows If we want to ensure the uniqueness of users and events, we need to add a unique constraint on the id of both of these labels: CREATE CONSTRAINT ON (user:User) ASSERT user.id IS UNIQUE CREATE CONSTRAINT ON (event:Event) ASSERT event.id IS UNIQUE Now if we run the test, we’ll only end up with one of each user: +----------------+ | userId | count | +----------------+ | 1 | 1 | | 2 | 1 | | 3 | 1 | | 4 | 1 | | 5 | 1 | | 6 | 1 | | 7 | 1 | | 8 | 1 | | 9 | 1 | | 10 | 1 | +----------------+ 10 rows We’d see the same result if we ran a similar query checking for the uniqueness of events. As far as I can tell, this duplication of nodes that we merge on only happens if you try to create the same node twice concurrently. Once the node has been created, we can use MERGE with a non-unique index, and a duplicate node won’t get created. All the code from this post is available as a gist if you want to play around with it.

Build a Wordpress deployment as a cdk8s construct.

Spring Roo is an rapid application development tool that helps you in rapidly building spring-based enterprise applications in the java programming language. Google app engine is a cloud computing technology that lets you run your application on Google's infrastructure. Using Spring Roo, you can develop applications that can be deployed on the Google app engine. In this tutorial, we will develop a simple application that can run on the Google app engine. Roo configures and manages your application using the Roo shell. Roo shell can be launched as a stand-alone, command-line tool, or as a view pane in the Springsource tool suite ide. Create it Fast and Effectively Most who create applications want to make them fast, and they want to make them effectively. What this means is that if they can figure out a way to create something that will both work for their users and also provide them with the speed of transaction that they need, then it is entirely possible that this will be precisely what they need to do in order to get the best results. Most are looking to Google search as a great way to get their apps out into the world, and it seems like this is as good of a place as any to start. Pushing out apps that can help the general population get the help they need with various projects means working with the most popular search engines in the world to make it happen. Thus, you should look to develop apps that work on Google in order to get the kind of results that you require. Prerequisite Before we can start using the Roo shell, we need to download and install all prerequisites. Download and install SpringSource Tool Suite 2.3.3. m2. Spring Roo 1.1.0.m2 comes bundled with STS. While installing STS, the installer asks for the location where STS should be installed. in that directory, it will create a folder with the name "roo-%release_number%" which will contain roo stuff. add %spring_roo%/roo-1.1.0.m2/bin in your path so that when you can fire roo commands from the command line. Start STS and go to the dashboard (help->dashboard) Click on the extensions tab Install the "google plugin for eclipse" and the "datanucleus plugin". Restart STS when prompted. After installing all the above we can start building the application. Conferenceregistration.roo Application Conference registration is a simple application where speakers can register themselves and create a session they want to talk about. So, we will be having two entities: speaker and presentation. Follow the instructions to create the application: Open your operating system command-line shell Create a directory named conference-registration Go to the conference-registration directory in your command-line shell Fire Roo command. You will see a roo shell as shown below. Hint command gives you the next actions you can take to manage your application. Type the hint command and press enter. Roo will tell you that first you need to create a project and for creating a project you should type 'project' and then hit tab. Hint command is very useful as you don't have to cram all the commands; it will always give you the next logical steps that you can take at that point. Roo hint command told us that we have to create the project so type the project command as shown below project --toplevelpackage com.shekhar.conference.registration --java 6 This command created a new maven project with the top-level package name as com. Shekhar.conference.registration and created directories for storing source code and other resource files. In this command, we also specified that we are using Java version 6. Once you have created the project, type in the hint command again, Roo will tell you that now you have to set up the persistence. Type the following command persistence setup --provider datanucleus --database google_app_engine --applicationid roo-gae This command set up all the things required for persistence. It creates persistence.xml and adds all the dependencies required for persistence in pom.xml. We have chosen the provider as DataNucleus and the database as google_app_engine because we are developing our application for google app engine and it uses its own data store. Applicationid is also required when we deploy our application to the Google app engine. Now our persistence setup is completed. 8. Type the hint command again, Roo will tell you that you have to create entities now. so, we need to create our entities' speaker and presentation. To create a speaker entity, we will type the following commands entity --class ~.domain.speaker --testautomatically field string --fieldname fullname --notnull field string --fieldname email --notnull --regexp ^([0-9a-za-z]([-.\w]*[0-9a-za-z])*@([0-9a-za-z][-\w]*[0-9a-za-z]\.)+[a-za-z]{2,9})$ field string --fieldname city field date --fieldname birthdate --type java.util.date --notnull field string --fieldname bio The above six lines created an entity named session with different fields. In this, we have used notnull constraint, email regex validation, date field. Spring Roo on the app engine does not support enum and references yet which means that you can't define one-one or one-to-many relationships between entities yet. These capabilities are supported on spring MVC applications but spring MVC applications can't be deployed on app engines as of now. Spring Roo Jira has these issues. They will be fixed in future releases(hope so :) ). 9. Next create the second entity of our application presentation. To create a presentation entity type the following commands on Roo shell entity --class ~.domain.presentation --testautomatically field string --fieldname title --notnull field string --fieldname description --notnull field string --fieldname speaker --notnull The above four lines created a jpa entity called presentation, located in the domain sub-package, and added three fields -- title,description and speaker. As you can see, the speaker is added as a string (just enter the full name). Spring Roo on google app engine still does not support references. 10. Now that we have created our entities, we have to create the face of our application i.e. user interface. currently, only GWT-created UI runs on the app engine. so, we will create GWT user interface. To do that type gwt setup this command will add the GWT controller as well as all the UI required stuff. This command may take a couple of minutes if you don't have those dependencies in your maven repository. 11. Next you can configure the log4j to debug level using the following command logging setup --level debug 12. Quit the Roo shell 13. You can easily run your application locally if you have maven installed on your system, simply type "mvn gwt:run" at your command line shell while you are in the same directory in which you created the project. This will launch the GWT development mode and you can test your application. Please note that applications do not run in the Google chrome browser when you run from your development environment. So, better run it in firefox. 14. To deploy your application to the Google app engine just type mvn gwt:compile gae:deploy it will ask you for app engine credentials (email id and password).

Most companies relying on Terraform for infrastructure management choose to do so with an orchestration tool. How can you govern Terraform states using GitLab Enterprise?

In this article, we will see why monitoring in real-time code-sharing platforms such as GitHub should be a top priority for any MSP.

This article dives deeply into GitHub event trending, why GitHub events are surging, and whether GitHub's architecture can handle the increasing load.

This article will show you how to use the Great Expectations library to test data migration and how to automate your tests in Azure Databricks using C# and NUnit.

Pull request vs. merge request, what is the difference?

Kubernetes is a colossal beast. You need to understand many concepts before it starts being useful. Here, learn several ways to access pods outside the cluster.

Problems with the old version of Kafka haven't been solved completely. Some shortcomings have been fixed while some problems have been introduced. The cycle continues.

Data streaming with Apache Kafka in crypto markets + financial services for cybersecurity / fraud detection via real-time threat intelligence

Learn how to audit your clusters for compliance with the latest Kubernetes Pod Security Standards without installing anything in the cluster.

Looking to migrate from ECS to EKS, but you're not sure where to start? Explore this guide and learn how to make your EKS journey easier.

This article compares two authentication service providers: Auth0 and Amazon Cognito. Both of them are cloud-based identity management services.

For today’s adventure, we want to build a Java microservice that connects to, and interacts with, graph data in a Neo4j AuraDB Free database.